1. Field of the Invention
The present invention generally relates to building wall structures and, more particularly, is directed to an insulated poured concrete wall with integral T-beam supports and the method of making same on site.
2. Description of the Prior Art
Concrete walls can be formed in various ways. Some are constructed from concrete blocks on footings, some can be formed by pouring or pumping in uncured concrete between rigid forms, and others can be made from prefabricated members which are becoming very popular. The traditional concrete block method for wall construction involves laying many courses of block, one on top of another, to build a vertical wall wherein each block must be individually placed and surrounded by mortar. This method is both time consuming and labor intensive.
Poured concrete walls have many benefits over other types of concrete walls. They can be quickly constructed, are relatively easy to construct, are versatile, and durable. The poured wall forms are generally planar structures and typically made of wood, aluminum, steel, or a combination of these materials. For poured walls, two series of coplanar wall forms are held in a spaced apart, generally parallel relationship to create the cavity which will form the concrete wall. The wall forms are typically held in the correct spaced apart relationship by a series of retaining (cross) ties extending between the form assemblies. The retaining ties commonly include holes formed in each end whereby pins are used to join adjacent coplanar forms together. Once the wall forms are in place, concrete is poured into the cavity between the forms and, after the concrete has cured, the forms are disassembled for reuse. The protruding ends of the retaining or cross ties are then broken off. One drawback of all concrete walls however, is that they are poor insulators. A typical concrete wall has an insulating “R” value of approximately 1.0.
To improve the insulating qualities of concrete walls, several methods have been developed for incorporating insulation boards, such as polystyrene sheets, within the concrete wall, or, on one or both exterior surfaces of the concrete wall. A concrete wall with 2.5 inches of polystyrene insulation on one side has an insulating “R” value of approximately 13.0; whereas, a concrete wall with 2.5 inches of polystyrene insulation on both exterior surfaces of the wall has an insulating “R” value of approximately 26.0.
One method to provide such an insulated poured concrete wall is set forth in U.S. Pat. No. 4,541,211 wherein an insulation board is sandwiched between two concrete walls. The insulation board is held midway between the pair of spaced apart wall forms by a special retaining clip 36 attached to the mid-portion of the cross-ties that retains the forms together and then concrete is poured into the two vertical void regions defined between the opposite sides of the insulation board and the opposite wall forms. Retainers 54 are used to mechanically connect the insulation board to the concrete wall layers on the opposite sides of the insulation board. In U.S. Pat. No. 5,744,076, insulation panels are provided on either one or both sides of the wall during the concrete pouring process. Elongated F-shape retaining strips that are attached to the form cross-ties are used to position the insulation panel(s) between the spaced apart opposite form walls. A similar method is taught by U.S. Pat. No. 5,987,830 but uses a different insulation retaining clip attached to the form cross ties. U.S. Pat. No. 5,992,114 teaches another method for insulating both sides of the concrete wall wherein spaced apart insulation boards are used for the form walls. In U.S. Pat. No. 6,438,917, the insulation board is provided with a groove along its vertical elongated edge that mates with retaining clips attached to the cross ties so as to position the insulation board(s) within the opposite sides of the forms and against the inner wall surface of one of the forms and/or also against the inner wall surface of the other form to thereby form a wall structure having insulation on both sides of the concrete wall. U.S. Pat. No. 6,634,148 teaches a similar method of making an insulated wall structure during the pouring operation wherein an elongated, notched T-shaped retaining strip which engages the cross-ties is utilized to position the insulation board adjacent one wall of the forms and to hold same in said position as concrete is poured into the cavity between the insulation board and the opposite wall of the form. U.S. Pat. No. 7,059,577 shows yet another method similar to the above prior art teaching wherein an elongated T-shape retainer strip is utilized to retain the insulation board in position against one wall of the form while concrete is poured into the open space between the insulation board and the opposite wall of the forms. The T-shape retainer is attached to the cross ties that connect together the spaced apart forms. US patent No. 2009/0173870 A1 describes a concrete forming apparatus with an outer form and an inner form held upright and in a spaced apart relationship via interconnecting tie rods 18. Between the inner and outer forms is a sheet of insulation 22 that's suspended along the tie rods (either centrally or offset). To stop the insulation from ripping when concrete is poured into the forms, the tie rods are passed through the insulation via a strengthening sleeve 28. Additionally, spacing rods 24 are used to keep the insulation away from the inner and outer forms and the spacing rods pass through strengthening spools 26 located perpendicularly within the insulation. U.S. Pat. No. 7,059,577 B1 patent describes an insulated concrete wall system employing inner and outer forms 12. The inner form abuts insulation panels 14, held into place and anchored to the poured concrete wall via “T” stud 16 which has a front face 26 that is visible in the finished wall and serves as a place for drywall to be anchored. The “T” studs also have an anchoring portion 30 which extends into the concrete wall beyond the insulation panels. The insulation panels, concrete forms and “T” studs are held in position via cross-ties 24 which pass between the insulation panels and through slots in the “T” stud 32. And U.S. Pat. No. 5,409,193 patent shows an apparatus and method for applying insulation to one or both sides of a poured concrete wall at the time the wall is poured. Insulation panels 12 are suspended inside the forms 22 using “F” strips 14 that affix to novel cross-ties 16 which hold the forms upright and spaced. Once the concrete is poured and cured, the cross-ties remain embedded in the body of the concrete, as do the “F” strips which hold the insulation securely against the wall. Each of the above methods includes in one way or another, specialized retainer clips that cooperate with the cross-ties. In addition thereto, each of the above methods produces a wall structure having a given-thickness concrete portion and then the insulation board(s) just adds to this given-thickness.
It is well known in the art, a concrete wall, such as a basement wall must be of a certain thickness, depending upon its vertical height, to support a predetermined load. Generally, the greater the height of the wall, the greater its thickness needed to support a predetermined load. And generally speaking, the thicker the wall, the more concrete is needed and, more concrete usually equates to more and increased costs. The above-described insulated, concrete poured walls inventions were basically directed to increasing the insulation “R” value of the poured wall, but none of them addressed the problem of the amount of concrete utilized in a given wall structure in an attempt to reduce the amount of concrete and thus the cost savings resulting therefrom.
The Zimmerman U.S. Pat. No. 4,570,398 patent, assigned to Superior Walls, introduced a new method for constructing basement walls. The key to the Zimmerman wall was the use of “precast concrete studs” for vertical height and strength. The precast studs were specifically designed to match their anticipated use. For a common residential basement wall, typically, the studs are two inches wide by six inches in depth and eight feet in height. These precast concrete studs are essentially rectangular in cross section but could contain a central narrower web to reduce weight and material cost. Steel reinforcing oriented along the length are cast into the studs to increase their strength, and several holes are formed in the central region to permit subsequent laying of electrical wires or water pipes through the studs within the walls that they form. Additionally, when the studs are cast, a pressure treated wood strip is cast onto one long, narrow edge, the edge that forms the interior basement wall, for easy attachment thereto of drywall or the like. These concrete precast studs are normally manufactured in a building, warehouse or shop and then transported to the basement site for installation. At the site, the studs are set on a base beam and spaced on two foot centers and extend vertically upward eight feet where a top wooden plate connects the concrete vertical studs together. After the stud construction is completed, the exterior walls of the basement are constructed. This begins with the attachment to the exterior of the concrete studs, one or more layers of rigid sheath insulation by pushing the sheath insulation against fasteners protruding from the concrete studs. A layer of wire mesh is then attached over the entire surface outside of the insulation, and then, concrete is sprayed onto the outer surface of the wire mesh at high velocity. The thickness of the sprayed concrete is between one to two inches thick. With the use of the precast concrete studs, the inventor was able to reduce the thickness of the concrete (maximum thickness of 2 inches) of the wall structure and at the same time increase the insulation R value of the wall structure by providing the insulation sheaths. The exterior of the wall structure would appear to be a monolithic smooth surface, whereas, the interior surface of the wall structure is stepped and offset with the plurality of spaced, six inch depth concrete studs projecting inwardly into the basement area from the insulation sheaths.
In a further improvement, rather than constructing the wall structure, with the precast concrete studs, on site, as described in the above '398 patent, Zimmerman utilized the precast concrete stud construction concept to manufacture prefabricated structural wall panels as shown and described in his U.S. Pat. Nos. 4,605,529 and 4,751,803 patents. The prefabricated wall panel is accomplished within an assembly jig which permits the wall panel to be manufactured in a horizontal position, so that conventional concrete delivery trucks can be used as a material source. Basically, in the assembly jig, spaced precast concrete studs with fasteners protruding from one edge are used to build the panel while oriented in a horizontal plane. Rigid sheet insulation is attached to the outside of the concrete studs and wire mesh is laid upon the sheet insulation. Concrete is then poured onto the insulation, the wire mesh and the protruding fasteners to form a continuous water-proof outer surface. Horizontal top and bottom beams are bonded to the concrete studs and are formed at the same time as the outer concrete surface. After setting of the concrete, the wall panel is one integral modular concrete structure which is transported on large trucks to a construction site for erection of several modules together to form the wall structure. Normally, this requires the use of a very large crane since the precast wall panels are extremely heavy. And in U.S. Pat. Nos. 4,934,121 and 5,055,252, Zimmerman describes and defines the method and means for connecting the prefabricated wall panels together at the job site. Basically, the panels are bolted together to form a rigid structure in thus forming an integral wall structure, such as the basement walls of a house. Here again, with the utilization of the precast concrete stud, the thickness of the concrete of the prefabricated panels that make up the final wall structure is considerable less than an equivalent block wall or standard poured wall. Also, we again have the same interior wall profile as in the above described '398 patented structure having a staggered offset profile with the precast concrete studs projecting inwardly further than the insulation panels. And yet another improvement to the Superior Wall prefabricated panels can be seen in U.S. Pat. No. 6,494,004 B1 (ZIMMERMAN) which shows a jig made of insulation panels that form the mold for a prefabricated concrete wall. The mold is assembled via a series of interconnecting foam panels, onto and into which concrete is poured forming the wall with integrated studs and insulation. Each stud is created using a metal channel 12 that holds three pieces of insulation in a “U” configuration, panel 16 at the base of the metal channel with panels 14 extending up along the sides. Suspended on panels 14 are panels 16 which comprise the inside surface of the concrete wall. Panels 14 and 16 are grooved to accept one another and stabilize the form during pouring. The resulting prefabricated wall has a continuous outer concrete surface with integrated studs and insulation comprising the inside of the wall; a stepped configuration.
The “Superior Wall” prefabricated panels have gained considerable market success in recent years and has many advantages and is ideally suited for certain construction projects and now there are several other companies that manufacture, sell, and erect similar such prefabricated panels, such as Titan Walls, Inc., Ideal Precast, and Specialty Precast Company. Some examples of other prior art prefabricated panels can be seen in the following: U.S. Pat. No. 5,313,753 discloses a prefabricated concrete wall 10 which consists of a continuous concrete planar face 12 integrated with studs 14 and adjacent insulation panels 16. The inner face of the studs has channels 20 housing polystyrene strips 50 for receiving drywall screws and the inner profile of the wall is planar. The wall 10 is attached to the footer via “L” brackets 32. U.S. Pat. No. 6,427,406 B1 patent teaches a preformed concrete wall that can be a cavity wall, best seen in FIG. 1, or a planar wall, best seen in FIG. 2. The concrete wall 1 has vertical studs 10 extending between a top beam 32 and a bottom beam 34, with integral studs poured into stud forms 12. The stud forms have rebar 20 that extends into the top beam and bottom beam for integration, and insulation 14 under the stud form abutting the interior face of the stud. The interior of the wall has either recessed insulation, creating a cavity wall panel as seen in FIG. 1 or thicker insulation, creating a planar wall panel as seen in FIG. 2. U.S. Pat. No. 6,338,231 B1 describes a precast concrete wall panel with a flat side 26 and a recessed side 28. The recessed side has a header 22 and footer 24, between which are horizontal ribs 32 that are vertically spaced. The recessed side is filled with insulation batts 34, which create a flat surface planar with the header and footer. The footer has a side recess 44 to accommodate rods or bars used to secure the wall panel to the foundation. The precast panels are lined up side by side to form the wall. And U.S. Pat. No. 7,530,203 B1 patent discloses a precast concrete wall system with an upper ledge that supports trusses for a below-grade floor system. The wall panel 10 is formed with a horizontal footer beam 12, an upper beam 15, and vertical concrete studs 13 extending between the two. Between the studs, the wall is insulated with a sheet of polystyrene 16. Each stud is covered with a foam “U” channel 35, which abuts the polystyrene sheets 16, creating a continuous layer of insulation on the interior of the wall. The wall described is mounted onto a bed of crushed stone.
One major disadvantage of using prefabricated panels is that for erection at the site, a large crane is required to lift and move the prefabricated panels into place and generally, these panels are set on a thin layer of compacted, crushed fine gravel which is in direct contrast to the long standing practice used for block and poured wall construction where a “concrete footing” (footer) is required for supporting the wall and the load supported by the wall. Although the prefabricated panel wall construction meets the code requirements in many areas, it is questionable over the long run whether such compacted crush stone base is equivalent to the traditional footer construction, especially in the northern areas of the country where freezing and thawing must be taken into consideration in the construction of such walls. Thus, there is a desire in the marketplace to have an insulated concrete wall structure that is constructed using the poured wall method and which wall structure is supported on a typical well-known footer and which wall structure provides a planar interior wall surface.